This invention relates to optical scanners in general and more specifically to an optical wave guide for directing light from a light source in the scanner onto the surface of an object being scanned.
Optical scanners are well-known in the art and produce machine-readable data which are representative of a scanned object, e.g. a page of printed text. Most optical scanners employ line-focus systems in which light from an illuminated scan line on the object is imaged by a lens onto a linear photosensor array or detector positioned remotely from the object. The linear photosensor array is typically a single dimension array of photoelements that correspond to small area locations along the illuminated scan line. These small area locations are commonly referred to as "picture elements" or "pixels." Each photoelement produces a data signal that is representative of the intensity of light from the corresponding pixel. The data signals from the photoelements are received and processed by an appropriate data processing system which may subsequently store the data on a suitable medium or generate a display signal therefrom for reproducing an image of the object with a display device such as a CRT or a printer.
Optical scanners and various components thereof are disclosed in U.S. Pat. Nos. 4,926,041 for OPTICAL SCANNER of David Wayne Boyd; U.S. Pat. No. 4,709,144 for COLOR IMAGER UTILIZING NOVEL TRICHROMATIC BEAM SPLITTER AND PHOTOSENSOR of Kent J. Vincent; U.S. Pat. No. 4,870,268 for COLOR COMBINER AND SEPARATOR AND IMPLEMENTATIONS of Kent J. Vincent and Hans D. Neuman; and U.S. Pat. No. 5,038,028 for OPTICAL SCANNER APERTURE AND LIGHT SOURCE ASSEMBLY of Boyd, et al.; and U.S. patent application Ser. No. 07/906,144 filed Jun. 29, 1992 for APPARATUS FOR ASSEMBLING COMPONENTS OF COLOR OPTICAL SCANNERS of Elder, et al., which are each hereby specifically incorporated by reference for all that is disclosed therein.
A hand-held optical scanner is an optical scanner which is moved across a scanned object, e.g. a page of text, by hand. Such hand-held optical scanners or hand scanners are also well-known in the art and various components thereof are disclosed in U.S. patent application Ser. No. 08/271,401 for Hand-Held Optical Scanner with Speed Control of McConica, et al. and U.S. patent application Ser. No. 08/271,333 for Light Path for Hand-Held Scanner of McConica, both of which are filed concurrently herewith, and the disclosures of which are each hereby specifically incorporated by reference.
Many of the early hand scanners were powered by an external power source such as a power unit connected to a wall outlet that was in turn connected to the hand scanner by an electrical cable. Such external power sources were usually necessary due to the significant electrical power required to operate the various scanner components. For example, the optical imaging assembly of a scanner typically comprises an illumination source such as an array of light emitting diodes (LEDs) or a fluorescent bulb. The scanner photoelectric conversion assembly (typically a CCD) also requires electrical energy as do the scanner speed detection circuitry and the scanner central processing unit.
As with most electronic devices, improvements in technology have allowed for the development of practical battery powered hand scanners. Of course, a significant advantage of a battery powered hand scanner is that the onboard power source and mass data storage assembly eliminate the need for external power connections or other connecting cables which tether the scanner to a fixed location. Such an arrangement also significantly improves the mobility and potential use applications for such a hand scanner.
While battery powered hand scanners have many advantages, they are still not without their problems. For example, a significant problem relates to short battery life, and efforts are constantly being made to reduce the electrical load on the battery by improving the efficiency of those components that place the largest drain on the battery, such as the light source for illuminating the scanning area and the speed control system for ensuring that the scanner is moved across the object being scanned at the optimum scanning speed. Battery life has also been increased by using an electric generator connected to the rollers of the scanner to recharge the battery as the operator rolls the scanner over the object.
Other problems common to hand scanners relate to the light source for illuminating the scan line. For example, it is difficult to provide illumination of sufficient intensity and uniformity along the length of the scan line while at the same time reducing specular reflections from the illuminated object, which can result in scanning errors. There is also a constant need to capture and direct onto the scanning area as much light as possible from the light source to allow lower power light sources to be used.
Consequently, there remains a need for a hand scanner having the features and performance typically associated with full sized desk top scanners, but in a portable, compact package. Ideally, such a hand scanner should be relatively easy and inexpensive to produce, while at the same time achieving efficient and uniform scan line illumination to increase battery life and reduce scanning errors. Scanning errors could be further reduced by reducing or eliminating specular reflections from the illuminated scanning area. Until the present invention, no such device existed.